Does anyone know where I can buy an animated circular saw prop? The only one I can find on the internet is a very expensive table prop, and I'm looking for something I can use in a chainsaw-like scare.

Why not modify one for haunt use?
Blade removed.
leaxn plate bolted over the base plate and blade slot. (its possible to do two plates with holes in the one closest to the motor, so it makes a kind of speaker and amplifies the sound a bit, that takes messing with).
plastic cover removed and screen glued on the inside of the vents for the motor (to prevent hair from being sucked in).
Groe it up and decorate it so its obviously a prop for that haunt, and keep track of it so no one puts a blade on it.
different brands require different measures but think it throuh and you should be fine. Also keep this in the back of you mind at all times....http://www.timesnews.net/article.php?id=9027062